At any rate, SSH randomart is mostly seen only when generating your keypair for
the first time. It’s a pretty interesting idea. A visual representation of a key
which makes it possible for humans to ID keys at a glance! It’s like having a CA
in your brain.

And there’s a very real application for these things in real life! SSH Host
keys! When you connect to the host, you have to handshake with the server, the
server identifies itself with its public key, and you can randomart it every
time!

Just pop into ~/.ssh/config and add:

VisualHostKey=yes

If you’re only on one machine, SSH will definitely let you know if a host key
changes, but what about new machines? Randomart gives you a way to usefully
remember host keys with your visual memory!

Another example: once I was working in a VM environment where all of the
machines were made from the same root image, and they all had the exact same
host keys. I noticed this because I had randomart on! I brought it to the
attention of the admins, and we got the host keys rotated, and the VM
provisioning procedure fixed as a result. That’s a pretty bad vulnerability
(prod had the same key as the build server, for example), and there’s no way I
ever would’ve noticed if I was just looking at the key fingerprints.